The incidence and geographic distribution of Lyme disease in the U.S. has increased steadily since its first description in 1977. Efforts to stem the spread of the disease through controlling the population of its tick vector and/or the mouse reservoirs of the disease have met with only limited success. The only approved human vaccine to protect against Lyme disease was removed from the market by its manufacturer further highlighting the need for new approaches to controlling the disease. In this project, we propose the development of a novel antibiotic targeted towards the mouse and tick reservoirs of the disease. This proposal combines the expertise in drug development of Dr. Kim Lewis? laboratory, the expertise in Borrelia burgdorferi biology in Dr. Linden Hu?s laboratory and the field expertise of Dr. Sam Telford?s laboratory. Treatment of mice with an antibiotic, doxycycline, has been shown to be highly effective in eradicating Borrelia burgdorferi from its reservoir hosts. However, there is legitimate concern for development of resistance, both in B. burgdorferi and in other organisms that may be exposed to the antibiotic should it be widely distributed. Doxycyline is an important antibiotic in the treatment of multiple different human infections and in some cases such as Anaplasma or Rocky Mountain Spotted Fever, the only approved agent available. We have identified an antibiotic, hygromycin A (HygA), that is highly active against B. burgdorferi but has limited activity against other human pathogens. Its mechanism of action is different from other human antibiotics. In our preliminary data, we have shown that it is very effective in clearing B. burgdorferi from infected mice when given orally by gavage or in bait formulations. In this proposal, we will complete the steps in developing HygA as an environmental antibiotic and perform a limited field trial on an isolated island off the coast of MA to test its ability to control infection rates in ticks and mice. In Aim 1, we will establish the pharmacodynamics, stability and safety profile of HygA in Peromyscus mice. We will determine optimum concentrations for bait distribution and perform simulation studies of bait uptake and clearance in caged animals. In Aim 2, we will attempt to induce resistance to HygA in B. burgdorferi and in other organisms of human importance that are likely to encounter HygA in the environment. We will confirm that if HygA resistance develops, it does not cause concomitant resistance to other antibiotics with human applications. Finally, in Aim 3, we will perform a limited field trial on an isolated island that is endemic for B. burgdorferi in ticks and mice to establish the efficacy of a HygA based reservoir targeted antibiotic approach. This study has the potential to have a major impact on human Lyme disease by controlling the organism in its major reservoirs. By utilizing an antibiotic that has a narrow spectrum of activity and does not have human applications, we hope to replicate the success seen with doxycycline, which is arguably the most successful trial of any environmental approach to eradication to date, without the attendant concerns for resistance.